var fs=require('fs');
var files=['a.txt','b.txt','c.txt'];
for (var i = 0; i < files.length; i++) {
	var fun=function (filename) {
		fs.readFile(filename, 'utf-8', function  (err,contents) {
			console.log(filename+': ' +contents);
		});
	}
	fun(files[i]);
}